Such drive slip regulators are in general well known and today can also be obtained commercially. Basically this drive slip regulator works in such a manner that the slip (i.e., the difference between vehicle velocity and wheel circumference velocity in terms of vehicle velocity) is regulated, a slip in the range of ca. 3% to 4% generally being permitted. If the slip is larger, drive performance is decreased and/or the driven wheel is braked by the excessive slip.
Determining the actual vehicle velocity, however, involves problems. For the first estimate, vehicle velocity is fairly well rendered by the non-driven vehicle wheels, assuming, of course, that these are turning freely and are not being braked. Vehicle velocity can be determined fairly well when the vehicle is being driven straight ahead, but not when passing through a curve, since the curve interior and curve exterior wheel circumference velocities can differ significantly from each other, depending on the turn radius. If, as is the practice with many vehicles, a diagonal division is chosen, such that for driven rear-axles the left front wheel delivers the reference velocity for the right rear wheel and the right front wheel the reference velocity for the left rear wheel, this can lead to significant errors because an excessive vehicle velocity (wheel velocity of the curve-exterior front wheel) is simulated especially for the curve-interior rear wheel.